A magnetic device includes a layer stack comprising a first ferromagnetic layer; a spacer layer on the first ferromagnetic layer; a second ferromagnetic layer on the spacer layer; a dielectric barrier layer on the second ferromagnetic layer; an insertion layer positioned between the second ferromagnetic layer and the dielectric barrier layer; and a fixed layer or an electrode on the dielectric barrier layer. In some examples, a magnetic orientation of the second ferromagnetic layer is switched by a bias voltage across the layer stack without application of an external magnetic field; an antiferromagnetic coupling of the first and second ferromagnetic layers is increased by the bias voltage applying a negative charge to the fixed layer or the electrode, and the antiferromagnetic coupling of the first and second ferromagnetic layers is decreased by the bias voltage applying a positive charge to the fixed layer or the electrode.